(SPENCER) - The search for a missing Owen County girl stretched into a second day Thursday as hundreds of people looked for any sign of the toddler.

During a Thursday afternoon briefing, Sgt. Curt Durnil said the massive search for 14-month-old Shaylyn Ammerman included search dogs, cadaver dogs, sonar and personnel from multiple law enforcement agencies. He also said the Federal Bureau of Investigation was involved in the case.

Rain made search efforts more difficult Thursday, but Durnil said search teams wouldn't be deterred. He also said two or three polygraph tests were administered Thursday, including one for the girl's father. Durnil said investigators were worried about her.

"A child is missing, and the house where the child is missing from is right over the White River," Durnil said. "We're not leaving any stone unturned in this case.

"She's been missing over 24 hours. We're worried. It's not good right now."

Interviews of persons of interest are being conducted, some for the second time. Evidence such as computers and cell phones have been collected and forensically examined.

Owen County Emergency Management have coordinated search and rescue efforts in full cooperation with law enforcement. The Vigo County Search & Rescue Team continues their efforts as well.

Resources have been pouring in from surrounding areas including all terrain vehicles and other search technology. The Indiana Conservation Officers are using sonar equipment in their effort.

The FBI is on scene and assisting local officers with their technology and resources along with state and local K9's both search and cadaver.

The National Center for Missing and Exploited Children is on the scene and relaying information from the case to their national headquarters.

Areas all over Owen County continue to be searched including areas near the White River and in proximity to the residence on Jefferson Street. Manhole covers and dumpsters are being searched as well.

Durnil said the search "won't end until we find Shaylyn." No arrests have been made, although there were seven to ten persons of interest that investigators wanted to talk to.

He also clarified that the case didn't meet criteria for an Amber Alert because there was no vehicle or suspect description available.

Investigators said Shaylyn was last seen at her father's home in the 400 block of West Jefferson Street in Spencer Tuesday night. Search efforts expanded Thursday.

Fears said several agencies were involved in the search across the county as they anticipated a rainy day.

"We've got Vigo County search and rescue coming in to assist us with some dogs. Our understanding is that (the rain) won't affect them too much," Fears said.

Shaylyn's father, Justin Ammerman, told police his mother put the child down for bed just before midnight Tuesday and when he woke up Tuesday morning his daughter was gone.

According to Shaylyn's mother, Jessica Stewart, the girl's father was having a party Tuesday evening. Ammerman says that's not true and he believes someone entered through the front door of the house and kidnapped her.

"Either somebody has a really, really big grudge over us or something, because I don't see anybody in this town ever doing something like this," Ammerman said. "Whoever has my daughter, return her please."

Stewart does not believe his story.

"He shows really no emotion. That is why I think that he is hiding something and I know when he is lying," said Stewart.

"I don't honestly think that he would hurt her purposely, I think he would not know what to do if it happened," said Shaylyn's grandmother Carol Stewart.

Shaylyn was reported missing to authorities in Owen County around 9 a.m. Wednesday. Investigators also served multiple search warrants in connection to this case.

Shaylyn is 20 pounds with blonde hair and blue eyes, and she was last seen wearing a white zip-up onesie with owls on it and a purple pacifier clipped on. She also had a blue and white Winnie the Pooh blanket.

If you have any information on Shaylyn's whereabouts please call Spencer police at 812-829-3932.